Determination of Minimum Meal Interval and Analysis of Feeding Behavior in Shaded and Open-Lot Feedlot Heifers

Abstract

Abstract. Feeding behavior contains valuable information that can be useful for managing livestock, identifying sick animals, and determining genetic differences within a herd. The objectives of this work were to determine the minimum meal interval and to assess changes in feeding behavior of feedlot heifers when exposed to various temperatures with and without access to shade. Feeding behavior data from feedlot cattle with and without access to shade were evaluated. Prior to evaluating feeding behavior data, the time between two eating events that should be considered a single meal (minimum meal interval) was determined. The length of this minimum meal interval impacts the interpretation of meal data. The minimum meal interval was first determined by analyzing feeding behavior data to determine the number of meals, average meal length, and total time spent eating at minimum meal intervals ranging from 1 to 60 min. These data were evaluated using rate of change based on interval differencing. A subsequent analysis identified the inflection point of the rate of change graph. A minimum meal interval of 10 min for finishing feedlot cattle was determined using this method. Feeding behavior data from 256 feedlot heifers (of four different breed types) were evaluated over two summer periods (128 heifers each year). Cattle were penned in one of 16 pens (eight shaded and eight unshaded). Individual feeding behavior data were collected every 30 s throughout the six-week summer period. Cattle decreased the time spent eating, average meal size, and number of meals as the THI increased. In addition, cattle provided with shade spent more time eating, with longer meal lengths over all THI categories.